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Special Issue Information

Dear Colleagues,

Polyphenolic substances are likely the most protean class of natural compounds and great challenges lie behind their study. They play a relevant role in plant ecophysiology, counteracting a wide range of biotic and abiotic factors and their chemical and biological plasticity reverberates in a plethora of applicative uses. Plant-derived polyphenols are in fact multi-purpose substances whose exploitation ranges from phytocosmetics to nutraceuticals, from medicinal and edible plants to pharmaceuticals, from pigments and dyes to fine chemicals and allelochemicals of agronomic value. As a consequence of that, for both ecological, environmental, plant, food and health sciences a proper knowledge of polyphenol variability, abundance and role represents a key feature. The analytical determination of these secondary metabolites in different matrices and the evaluation of their biological properties are of crucial relevance also in a number of industrial fields. As these topics have been the focus of many recent technological improvements, contributions for this special issue, both in form of original research and review articles, may cover the development, validation or the improvement of any new applied method devoted to the chemical (chromatographic, spectroscopic, metabolomic, chemometric and sensorial), biochemical and biological evaluation of polyphenolic substances in any crude or processed plant material, biological fluid and product (including foods, drugs, biomasses, herbal products, dyes, animal feeds and agroindustrial wastes). The presented methods must demonstrate their applicability on real samples and not exclusively on standard substances. Fingerprinting methods capable to monitor polyphenols during different production processes, during storage in crude drugs and finished products and capable to elucidate their fate in vivo (in both animals, plants and environment) will be particularly welcome. Review articles must cover the state-of-the-art and trends in the analysis of specific sub-classes of polyphenolic substances or the perspectives regarding the applicability of definite techniques. Authors considering the submission of a review are kindly asked to provide in advance to the guest editor a brief outline of the subject matter of their work. Manuscripts regarding new methods for the evaluation of polyphenol bioactivity are also suitable for submission. In particular, innovative protocols and methods based on chemical or biological systems for the evaluation of in vivo and in vitro bioactivities of pure polyphenols and/or polyphenol-rich products or extracts will be taken into consideration, on condition that they are properly characterized from a phytochemical standpoint.

“Chimarrão” and “tererê” are maté (dried, toasted and milled Ilex paraguariensis leaves and stemlets) beverages widely consumed in South America. This paper describes the application of HPLC-DAD-ESI/MS method for the identification and quantification of caffeoylquinic acids (CQA), flavonol glycosides and purine alkaloids in

“Chimarrão” and “tererê” are maté (dried, toasted and milled Ilex paraguariensis leaves and stemlets) beverages widely consumed in South America. This paper describes the application of HPLC-DAD-ESI/MS method for the identification and quantification of caffeoylquinic acids (CQA), flavonol glycosides and purine alkaloids in these beverages. The beverage samples were prepared from commercial lots of maté from Southern Brazil. The caffeoylquinic acids, 4,5-diCQA, 3-CQA, 5-CQA, and 4-CQA were the major compounds, having 238–289, 153–242, 183–263, and 123–188 μg/mL, respectively, for chimarrão and 206–265, 122–218, 164–209, 103–169 μg/mL, respectively, for tererê. Caffeine also had high amounts while glycosides of quercetin and kaempferol were found at much lower levels. The individual antioxidant activity was also determined by an on-line system that measured their ABTS•+ radical scavenging activity, showing that the antioxidant capacity was not proportional to the concentrations of the phenolic compounds. 3-CQA, quercetina-3-O-ramnosylglucoside, and quercetina-3-O-glucoside were the major contributors to the antioxidant capacity, although the quercetin glycosides had concentrations less than 10 times that of 3-CQA.
Full article

The comprehensive identification of phenolic compounds in food and beverages is a crucial starting point for assessing their biological, nutritional, and technological properties. Pomegranate (Punica granatum L.) has been described as a rich source of (poly)phenolic components, with a broad array of

The comprehensive identification of phenolic compounds in food and beverages is a crucial starting point for assessing their biological, nutritional, and technological properties. Pomegranate (Punica granatum L.) has been described as a rich source of (poly)phenolic components, with a broad array of different structures (phenolic acids, flavonoids, and hydrolyzable tannins) and a quick, high throughput, and accurate screening of its complete profile is still lacking. In the present work, a method for UHPLC separation and linear ion trap mass spectrometric (MSn) characterization of pomegranate juice phenolic fraction was optimized by comparing several different analytical conditions. The best solutions for phenolic acids, anthocyanins, flavonoids, and ellagitannins have been delineated and more than 70 compounds have been identified and fully characterized in less than one hour total analysis time. Twenty-one compounds were tentatively detected for the first time in pomegranate juice. The proposed fingerprinting approach could be easily translated to other plant derived food extracts and beverages containing a wide array of phytochemical compounds.
Full article

Fourteen brands of resveratrol-containing nutraceuticals were evaluated in order to verify their actual resveratrol content and to control if their health-promoting properties are related to manufacturing quality. Products included pure resveratrol capsules or multi-ingredient formulations with standardized amounts of resveratrol and other phytochemicals.

Fourteen brands of resveratrol-containing nutraceuticals were evaluated in order to verify their actual resveratrol content and to control if their health-promoting properties are related to manufacturing quality. Products included pure resveratrol capsules or multi-ingredient formulations with standardized amounts of resveratrol and other phytochemicals. Samples were analyzed for total trans-resveratrol, flavonoids, procyanidin, polyphenol content and the results were compared with the content declared on-label. Only five out of 14 brands had near label values, compliant with Good Manufacturing Practices (GMP) requirements (95–105% content of active constituent), four products were slightly out of this range (83–111%) and three were in the 8–64% range. Two samples were below the limit of detection. The greater the difference between actual and labeled resveratrol content, the lower was the antioxidant and antiproliferative activity strength. Dietary supplements containing pure trans-resveratrol exhibited a greater induction of differentiation towards human leukemic K562 cells when compared to multicomponent products. Great differences currently exist among resveratrol food supplements commercially available and GMP-grade quality should not be taken for granted. On the other side, dosages suggested by most “pure”, “high-dosage” supplements may allow a supplementation level adequate to obtain some of the purported health benefits.
Full article

The analysis of major and minor flavonoids, and antioxidant capacity of stems, leaves, flowers, unripe seeds and ripe seeds of common and tartary buckwheat plants collected during different growth periods was addressed in this study. The highest rutin contents were observed in flowers

The analysis of major and minor flavonoids, and antioxidant capacity of stems, leaves, flowers, unripe seeds and ripe seeds of common and tartary buckwheat plants collected during different growth periods was addressed in this study. The highest rutin contents were observed in flowers and leaves collected from common and tartary buckwheat at early flowering as well as flowering and seed formation states. A low quercetin contents were found in all studied aerial part of buckwheat plants. Quercitrin (quercetin-3-rhamnoside) was only found in flowers collected at different growth periods while flavone C-glucosides were accumulated preferentially only in unripe seeds collected from common buckwheat at an early flowering state. The rank of antioxidant capacity provided for aerial parts of common and tartary buckwheat at early flowering state was as follows: flowers > leaves > stems. The highest contribution of rutin to the antioxidant capacity of the aerial parts of common and tartary buckwheat was found for stems followed by leaves, flowers and unripe seeds. The results demonstrate that flowers from common and tartary buckwheat collected at early flowering as well as flowering and seed formation states have the future potential to be a useful food ingredient.
Full article

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules

Phenolic compounds are well-known phytochemicals found in all plants. They consist of simple phenols, benzoic and cinnamic acid, coumarins, tannins, lignins, lignans and flavonoids. Substantial developments in research focused on the extraction, identification and quantification of phenolic compounds as medicinal and/or dietary molecules have occurred over the last 25 years. Organic solvent extraction is the main method used to extract phenolics. Chemical procedures are used to detect the presence of total phenolics, while spectrophotometric and chromatographic techniques are utilized to identify and quantify individual phenolic compounds. This review addresses the application of different methodologies utilized in the analysis of phenolic compounds in plant-based products, including recent technical developments in the quantification of phenolics.
Full article

Grape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that’s why their analysis and quantification are of primordial importance. The extraction of phenolics

Grape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that’s why their analysis and quantification are of primordial importance. The extraction of phenolics from grapes and from wines is the first step involved in the analysis. Then, several analytical methods have been developed for the determination of total content of phenolic, while chromatographic and spectrophotometric analyses are continuously improved in order to achieve adequate separation of phenolic molecules, their subsequent identification and quantification. This review provides a summary of evolution of analysis of polyphenols from grapes, wines and extracts.
Full article